The increased utilization of unmanned air vehicles has focused upon the demand of the possibility to land with great precision and safety at a certain landing place, at the ground, at buildings or at mobile vehicles. The problems related to the landing procedure comprise questions as to estimation of the position, relative velocity and safety for persons and vehicles. In many applications the landing will take place in the vicinity of systems present and persons occupied by manual landing. The automatic flying movement should thus show a performance and characteristics similar to manual landing. This is especially true regarding landing at vessels at sea with helicopter. Today there are several assisting systems intended to assist the pilot and increase the safety in the very moment of landing. For a helicopter the rolling of the vessel and the wind conditions around the vessel are especially important. For manned helicopters the landing is often carried out with the assistance of several persons at the deck of the vessel, partly for guidance, but also for anchoring. Often this work is carried out during bad conditions and with a high risk for personal injuries.
the present invention relates especially to these conditions by giving the flying vehicle a landing plate, that adapts to the actual attitude of the helicopter. This may facilitate manned landings and unmanned landings and starts from vessels and other mobile vehicles. By combining this invention with known technologies within positioning; optical sensors and vacuum technology a new and safe landing system may be created, preferably for automatic flying vehicles.
A system for this may typically comprise combinations of the different system components (a) navigation system, (b) course planning system with prediction, (c) safety system, (d) landing plate with locking device and (e) undercarriage at the air vehicle. The system described is developed for helicopters, but it may partly or completely be used for flying vehicles with wings. The system may be used for unmanned as well as manned vehicles. As example of landing place a terrain lorry or a vessel may be mentioned.
(a) Navigation System
The navigation system for landing may differ from the one used for normal flying. They show different requirements for precision of positioning. This requirement is increased when the landing place is located at a mobile vehicle. The navigation system operates from an outer point and in to the landing plate. As an example may be mentioned a dGPS (Differential Global Position System) system with receivers at the landing plate as well as at the flying vehicle. This system may also be implemented with the aid of camera, optics or other sensors such as inductive, acoustic or laser based sensors. These are examples of technologies earlier used to measure mutual spatial relationships at mobile vehicles such as cars, vessels and helicopters.
(b) Path Planning and Prediction
A pre-requisite for the system to operate with a mobile landing plate is a system, that can predict the future positions of the different vehicles. This landing progress thus comprises algorithms and software in order to predict the mutual positions of the vehicles. Often this is implemented by different filters such as Kalman-filter or the like. The prediction is carried out with information combined from sensors, primarily located at the vehicle carrying the landing plate and at the flying vehicle. Portions of the sensors of the navigation system are included in this part system. Sensor system and algorithms may be separated in the different phases of the landing progress. A system for measuring the relative distance between the landing plate and the vehicle either uses the sensor system of the landing vehicle or that of the flying vehicle, both in combination and separately.
(c)Safety System
In order to prevent an automatic landing to cause an injury at the landing place a system with safety limits may be created within the frame of the information handling system. These limits form corridors and sectors in the air space around the landing vehicle where the air vehicle is allowed to be present. This is similar to the different approach systems, that can be found at airports. These limits are intended to protect staff or vital portions of the landing vehicle. The predicted flight path is controlled in that the flying vehicle passes a number of control frames in the predicted flying corridor under its way towards the landing plate. In the case of a mobile landing vehicle these control frames will follow the landing vehicle. The safety system comprises functionality, that can judge if the landing progress shall be interrupted, both in a controlled way by one further approach trial or by a non-controlled landing within a predetermined space at a safe distance from the intended landing place.
(d) Landing Plate and Locking Device
The critical moment of the automatic landing is the very setting to ground and the immediate locking of the flying vehicle. Traditionally the very landing moment occurs at the most favorable point of time. In the case of landing of an helicopter at a vessel the pilot must often hover above the landing plate a short time to get an idea of the movements of the vessel. Different visual aids mounted at the vessel are used to facilitate this observation. For the very locking there are different solutions. An example of this is formed by harpoon-like fastening hooks, that are shot down into the plate from the helicopter and educated staff, that lock the helicopter at the landing plate by their own body weight and sand bags. In many cases this demands a special design of the surface of the landing plate and belonging lock means. Especially critical is the friction, that is created between the surface of the landing plate and the undercarriage at the flying vehicle. For a safe landing it must be possible to interrupt the landing progress immediately until the motor of the flying vehicle is stopped.
(e) Undercarriage at the Flying Vehicle
The undercarriage at a helicopter has several different functions, partly it shall aid as an assistance means at landing and start, but also as a protection at a possible crash or hard landing. Thus there are rules regarding its design. The undercarriage thus often is designed like skis. Its design in marine connection differs somewhat from that in landbased helicopters.